1. Field of the Invention
This invention relates generally to drilling equipment used particularly in the hydrocarbon production industry, and specifically to a spider system and method for running or raising tubulars in a well.
2. Background Art
In the hydrocarbon production industry, tubular goods, including drill strings, casings and tubing, referred to simply as tubulars, must at varying stages be run, i.e. lowered, into or raised from a well. An elevator is a device that is carried by the drilling rig's traveling block or a top drive, which supports the tubular for the purpose of raising or lowering it. An elevator may clamp along the side of a tubular using slips and dies to exert a radial clamping force on the tubular wall, or an elevator may use a bushing to support the tubular at the lower lip of a box connector.
A spider, much like an elevator, is a device which supports a tubular to prevent it from descending into a well when it is not held by an elevator. Unlike an elevator, however, a spider is designed to remain on the drilling deck and is typically not moved vertically. When the elevator, suspended by the traveling block, nears its high limit of travel (when raising a tubular) or its low limit or travel (when running a tubular), or when a stand is required to be added or removed, the elevator must be repositioned in order to continue the operation. The spider supports the tubular prior to the elevator releasing the tubular. Thus, the tubular is held in place while the elevator is repositioned. Once the elevator carries the tubular at a new location, the spider is disengaged allowing the tubular to freely pass through the spider or for the spider to be moved completely clear of the tubular.
Some elevators and spiders used today employ power operated internal mechanisms, e.g., power doors and/or power slips. The powered elevators and spiders are commonly hydraulic, but can be pneumatic or electric.